Kylo always wanted a pet but was never allowed one as a Jedi because it was an attachment and Jedi aren't supposed to have those. So when he comes across Millicent trotting about the halls of the Finalizer, he's delighted and adores her. And even though he kind of hates Hux, they make peace because it upsets the cat if they argue.

So Hux starts bringing Millicent into more briefings, trains her to walk on a leash and lets her hang out on the bridge with him, and at least once when Kylo is wrecking shit, Millicent only has to give a distressed meow for him to stop, drop everything and go reassure her it's alright. Kylo even asks if Millicent (who he totally calls Millie) is alright post-TFA when he wakes up from the asskicking he received from Rey.

Can be gen or Kylux, this meme just needs more Millicent.